Means for forming tubes from tubular blanks



W. A. CURTIS MEANS FOR FORIIING TUBES FROM TUBULAR BLANKS Sap t. 12, 1950 Filed May 18, 1945 I INVENTOR. Wczlierd Claim B Y 7422 MM &9

Patented Sept. 12, 1950 snai -mo T mman *bulat' 'blanks'i and has to dd 'wiph a} pro e s of redu ing the' wall thickness of='ituhula1*metal blanks jzwith" corfespon'din elon'gatio rifi tnqeor While shaping the resultant tube i to desireddn thickness of the blank reduir'es th'e use of a mu1- tiplicity of dies anaanneaunger "the blankiafter FeaGh" drawing" operation; which is j ex ensive and 'time consuming) My invention is dir'eetedto aprocessand means wherebytlie wall thickness of"a""tubularnietal P blank may "bel'snbstantially reduced; withco'r'r 'es'p'onding elongation of' th'e blankf'in a single operation and withoutithe 1 "use of expensive flies of other 'parts' subje'ct -"to "x' ss'i've' wear per- -=m'r'mm the process v k -blank ,-:imou'nte'd-'on -a"n"'=inter1or mandrel; is subje'cted 1:0 radial" and axialgpir ssure by forming means; with i'elative -movemefit "betweensuch "'nieans and trie -blank lengthwise "of the 1 latter, wherebythemetarof the wan dig the blankis di's placed 'fto-' desired depth and is redistiibuted lengthwise of the -bla'nk' so as to cans e1 .:.thereo'f:-:'More specificall' thefiniandr l iblank -mounted thereon avenged mough 'a Y rcoaxial forming assembly comprising awplni ality 5 f: rotatably mounted foririing fiiemb'ers defining t'vith the blank 'aforming passage-having an anmular. .exit portion or afr'adius greater the that I-O'f Iath 'mandrel by the"?- desired wa11 thickness bf athe tube tobe;-:producedi.;and a substantially con- :ica'l entrance portion;.of::greatr diameter its zgentranceaend "than:-the.aoutside. 'diamete of- 'the ;.;biank;leading"to ;ands. conver'ging toward the ekit zportionia--zThe assembly: is v rotated; at appropriate qspeed. and... upon; relative,rmovenientr betweeii the -,.-a ssembly;and the bl'ank lengthwise-16f the latti', the; iorminge'memberspeapply akial'giand a radial 102 1 1 8 :pressures to the iwallotithe iblank "with 1 the {area :ofsr application; of:atsuchzfpressui'esx advancing; along .-the;blank;where'by theirwall thereof is reduced in thickness to the desired extent filqt lfiq la tanqtedwt wama-thezmandrel zandia 2,522,2 57- FOR FORMING-TUBE mom ii unis-"Cleveland," Ohio, pssi 'n'or to n; 2Blshopjc8z, Babcock' Manufacturing Company Cleveland, 0hio, a corporation of-Ohio l T his inv'ention relates "to the working "oftumy invention,' the tubular msgsari oylindrica'i -body *portlom thou'gh within the fibroader concept of my invention any "other anal- 'og'oii s forming members *may be used; Further bjects "and advantages of my inventiony'vill' ap- -pear mm thedetail'descriptions In'the diawing's:

to the' vall-ofathe blank; I Figllie" 4 is a front view, with the 'lower' haif of the from} i'etain'r ring Omitted and. the lower half of the roller cage shown "in; section; or the Figure 5isafragmentary-sectionalview, on an enlarged'scal'e', taken substantially ofilirle 8-] jot-Figure 4 put-showin a blankonthemandrel with 'the wal1 of' the blank 1311113111611 150i a portion or; its jle'ligth by the I axial and radial pressures applied thereto by the rotatablymounted form- -'ing{mmbe s"of-theassembly; y "In"Fig u1es-;1*and 2 'of'zthedrawingsl have indicated a ehuck lcor the head stock' o a t-lathe,

this chu'ck i being 1 of conventional type 'andrequiring no detailed description. Chuckj -10 is -alig'ned with chuck} Ilg-or"similar'holding' means, of the tail stock at: theflath? A cylindrical maindrel 12: is mounted; at one enti in emb r or ehuck l- I andP extends therefrom in' eoai'ial 'rel ation to" a forming as senibly l ti'secure'd' m chnok '55 the: d'iameter of theqespective :r'ou'er's 22 Figure 1 'ise. emi-diagranimatle sectionalyiew 3 be understood. Each of the rollers 22 comprises a cylindrical body portion 22* and a tapered portion 22 ofsubstantially frusto-conical shape and I the tapered portions 22 of the rollers to the wall tapering toward the mandrel l2. The diameter of cage 2! is such -as to hold the rollers 22 in contact with race l4, at the inner circumferential face thereof, with the cage 20 centered in the assembly It. It will be seen that the back retaining ring llextends radially inward beyond race l4 sufllciently to provide an abutment orstop for the outer ends of the rollers 22, which are flat at their outer ends as shown, and the front retainer ring l1 extends radially inward beyond race l4 a sufficient distance to provide a stop for the flat inner ends of the rollers. In that connection, the rollers flt fairly snugly between the retainer rings is and I1, but not tightly, and the cage 2|! fits fairly snugly about the body portionsoi' the rollers but also not tightly. The rollers 22 have a slight amount of looseness or play to accommodate themselves to the surfaces being acted upon, but without excessive tilting of the rollers such as would tend to cause them to bite into the wall of the blank being operated upon. From the above description of the assembly l3, it will be apparent that the rollers 22, when produced, as during rotation of the assembly ll, define between them a space or opening having a cylindrical exit portion and a substantially conical entrance portion extending to and converging toward the cylindrical exit portion.

In Figure 1 I have shown a cup shaped metal blank 24, produced in a known manner, closed at one end by an end wall 25 pierced at 26, this blank being mounted upon the end portion of mandrel l2 adjacent the assembly I 3. The mandrel I2 is of substantially the same diameter as the inside diameter of blank 24 and fits snugly therein, so to support the circumferential wall of the blank against inward radial displacement. The tapered inner end portions 22 of the rollers 22 of assembly I3 define a substantially conical entrance portion, as above noted, of a diameter at its entrance end greater than the outside diameter of the blank 24, and the body portions 22' of the rollers 22 define a substantially cylindrical exit portion, of the space or passage above referred to, of a radius greater than. the radius of the mandrel l2 by an amount equal to the desired wall thickness of the tube to be formed from the blank.

After the blank 24 has been mounted upon mandrel l2 in proper relation to the assembly II, as above described, the chuck H, and with it the mandrel l2 and blank 24, is moved toward the assembly I! so as to introduce the blank 24 into assembly IS in coaxial relation thereto and thereafter move it lengthwise through the assembly. During movement of the blank 24 into and through the assembly It, the assembly is rotated at appropriate speed. Introduction of the blank 24 and the mandrel I 2 into the assembly I3 brings the circumferential wall of the blank into pressure contact with the forming members or rollers 22, which are then caused to rotate about their own axes while also rotating with the assembly l2 about its axis of rotation. In the continued travel of the blank 24 through the assembly It, the tapered end portions 22 of the rollers 22 exert considerable pressure on the wall of the blank, this pressure in part being directed lengthwise or axially of the blank toward the other end thereof, there also being a larger component of radial pressure applied by of the blank. In that manner the metal of the wall of the blank is-displaced to a depth determined by the, difference between the radius of mandrel l2 and the radius of the cylindrical passage or space defined between body portions 22* of the rollers 22. As the metal is displaced from the wall of the blank it is redistributed towards the other end thereof by the tapered end portions of the rollers, and the thinned area of the wall of the blank is rolled down and smoothed by the cylindrical body portions of the rollers, and shaped to substantially uniform wall thickness about the mandrel l2. During the operation of reducing the thickness of the wall of the blank the rollers 22 provide, in eflect, with the mandrel l2, a forming passage having an'annular exit portion and an entrance portion leading toand tapering toward the exit portion, so that when the blank is advanced by the mandrel through the assembly l3 in pressure contact with the forming'members or rollers 22, the metal of the wall of the blank is displaced and redistributed in the manner above stated. In the continued advanceof the blank through the assembly, the displaced metal of the wall of the blank is continuously shifted or displaced toward the opposite or open end of the blank, the net result being that as the .wall of the blank is reduced in thickness it is proportionately elonated.

It will be seen that the rollers 22 have small area of contact with the wall of the blank, such contact bein restricted to substantially line contact. It will also be clear that since the forward or inner ends of the rollers 22 are of substantially conical or tapered formation, the peripheral speed of the tapered end portion of each roller increases outward or toward the body portion of the, roller, and the metal of the wall of the blank is displaced in very small increments. I consider that of importance in that desired flow of metal along the wall of the blank lengthwise thereof is readily initiated, after which the metal may readily be displaced from the wall of the blank and kept flowing continuously therealong. In that connection, the travel of the rollers about the wall of the blank in pressure contact therewith, in the continued rotation of the assembly I 3, heats by friction and pressure the metal of the blank wall so as to render it more flowable than would otherwise be possible without this heating eflect, which also contributes to ready displacement and flow of the metal oiv the wall of the blank in the manner stated. It will be appreciated that some force is required to advance the mandrel l2 and the blank 24 mounted thereon through the rotating assembly I! and that the forming members or rollers 22 are subjected to outward radial thrusts. The race i4 is of adequate mechanical strength to take such thrusts and, since the rollers are rotated above their respective axes during the forming operation, neither this race nor the rollers are subjected to objectionable wear. Also, during travel of the mandrel and the blank through the assembly it, the rollers are subjected to axial thrust, which is taken up by the black retainer ring l5. seated in the chuck I 0 of the lathe, the

parts being of adequate mechanical strength forthat purpose.

The taper of the inner portion 22 of the replaced and redistributed without risk of crackthis ndof the "roller amine emu-mamma 'wa lottm blank i withi t er nse 91 ti ja'bout, thirty-three. ;degrees to. twenty-seven desures ammusiier ap arsto avedeflnite elation to he shea ,zreesr depending up'the degree iofhar'dne'ss tr the brass". I haveiound that janangle of approximallyijthirty degrees fgivesfthe ,rron r ivimen etween ;.tne "shear strength iandLth'e compression strength crjsqazc deep erawingg brass of any degree of hardness; whereby themaximum advantage of both isattained [Since the taperedends I22 .oiftherollers 22 i have substantiallyline contact only with the wall of theiblanktlie thinnedarea'of suchwallfneed' not be subjected to substantial. lengthwise tenskin by the mandrel i2 inorder to'eilect rapid displacement andred is'tributlon "or the metal of the blan'kin the manner/above stated. That is of importance in avoiding subjecting the thinned area of the blankwall to stresses such as would be apt to cause rupture or tearlng thereof, and renders possible very substantial reduction in thickness of the wall of a'tubular blank in a single continuous operation. Ihave reduced the wall of a tubular brass blank, formed 0180- brass, from a thickness of .04?" to .025" in a single continuous operation, and it is possible by proper:

ly. relating the rollers 22to. the mandrel l2, and

drivingthe forming assembly ii at appropriate speed,- to reduce the wall of the blank to a much greater extent.

.Referring more particularly to Figure 5, as the blank 24 is advanced through; the assembly l3, the metal displaced from the wall of the blank by the tapered inner end portions of'22 of the rollers 22 may, in certain cases, tend to pile up in advance of the rollers somewhat in the manner indicated at 30, it being understood that this piling up of the displaced metal is exaggerated for purposes of illustration. In certain cases the.

displaced metal might tend to accumulate to such an extent as to interfere objectionablywith the continuous operation of the process. It is possible, when that occurs, .to back out themandrel with the partially reformed blank and remove the bar or rib of displaced metal bycutting or filing it away, or in any other suitable manner, and to then reinsert the mandrel and the blank I 5 h? r 0 f ...-.2? an 1 2 1 b ank b nw ated is. (i meme 6316 "rates of: aljparticles lbetweenathe body. Dortionsfo'f .the'.irollers'land'gthe wall of [the blank wdqri nd h tm gn wer sub n j acti n-ab y} rpughfand; in addition, might. cause cracking or rupturing of the thinned blank wall.

. It will b .seen that by my inventionl render it possibleto reduce: lsubstantially the wallfth icknless a i b l ank; sum ed. in F r an 5,.Tand' to elongate correspondingly the wall-oi the blank so astoproducean elongated rela- .tivelyjthinned walled tube, in; a; single continuous onerau ngjr accomplish this re lt. by me ns or comparatively simple construction not subject to excessive ,wear. in] use and". which is. much less expensive than {thedie equipment which would be required foreffectinga considerable reduction in wall thickness of a tubular blankbyrknown drawing-operations. While; in the above description ofmy-invention I have referred to moving the Emandrel '12 and the blank 24 mounted thereon through the assembly i3 'whilerotating the latter,-it will be understoodthat the relative; movements of the parts may be reversed; that is, the: mandrel l2 and-the blank 24 mounted thereon mayremain stationary as'to axial movement thereof and the assembly l3 may. -be moved lengthwise of the blank while being rotated'thereabout. Further,

instead of rotating the assembly ,tne mandrel I 2 with the blank 24 mounted thereon may be rotated. whilejthe assembly l3 remains stationary with respect to' rotation. Obviously axial movement may be imparted to. both the assembly l3 and the mandrel l2 and the blank 24 mounted thereon, and either the assembly l3 or the mandrel l2 with the blank 24 mounted thereon, or

both, may be rotated. In other words, myv inintothe assembly l3 and continue theoperation.

In order to avoid such temporary interruption of the operation, however, I preferably provide means wherebyobjectionable burs or excessive displaced meta-l may be removed by the operav tion of the rotating assembly l3, whereby the wall of the blank may be reduced in thickness to the-desired extent and correspondingly elongated in a single continuous operation. To that end, the cage 20 is formed in lengthwise section as shown in Figure 5, having its forward portion 2! reduced in thickness or radial extent and of rectangular cross section, the main or bodyportion of the cage 20 also being of substantially rectangular cross section, and the cageas a whole being made of suitably hardened steel. The forming of the cag 20 in the'manner stated provides a sharp edged point or cutting-element 20 at the forward ends of the respective roller revention comprehends, in its broader aspects, imparting relative movement to the blank and the forming assembly axially thereof while also imparting relative rotation to the blank and the forming assembly, with the forming members or rollers in pressure contact with the circumferential wall of the blank, regardless of which particular member or members of the apparatus are rotated or moved axially. As above indicated,

and as will be understoodby those familiar with the metal working art, changes in details of my invention, with respect to both the process and the means for practicing it, may be resorted to without departing from the field and scope of my invention, and I intend to include all such variations, as fall within the scope of the appended claims, in this application in which the preferred form only of my invention has been disclosed.

I claim; I

1. In a roller assembly, a race member of substantlalradial and axial extent having an inner cylindrical surface, a ring secured tothe outer end of said race member projecting radially inward thereof, a ring secured to the inner end of said race member projecting radially inward thereof, a cage disposed in substantially concentric spaced relation to said inner surface of said race member and to said rings, said cage having therein axially extending circumferentially spaced slots, and a plurality of rollers respectively mounted in said slots between said rings restrained thereby against axial movement relative to said race member, each of said rollers comprising a cylindrical body portion having at its inner end an inwardly tapering element, the bod portions of said rollers seating against said inner surface of said race member and defining a substantially cylindrical exit portion of said assembly, said tapered elements defining a substantially conical entrance portion of said assembly converging toward and leading to said exit portion.

stantial radial and axial extent having an inner cylindrical surface, a cage disposed in substantially concentric spaced relation to said inner surface of said race member, a plurality of rollers mounted in said cage for free independent rotation, and means restraining said rollers against axial movement relative to said race member, each of said rollers comprising a cylindrical body portion having at its inner end an inwardly tapering element, the body portions of said rollers seating against said inner surface of said race member and defining a substantially cylindrical exit portion of said assembly, said 3,,

tapered elements of the rollers defining a substantially conical entrance portion of said assembly converging toward and leading to said exit portion, said cage being provided adjacent the inner ends of said rollers with spaced cutting eements extending radially inward thereof.

3. In a roller assembly, a race and a plurality of circularly caged rollers rotatably mounted therein, each comprising a, cylindrical body portion having at its inner end an inwardly tapering 2. In a roller assembly, a race member of subelement, the body portions of said rollers having bearing contact with the inner face of said race and defining a substantially cylindrical exit portion of said assembly and said tapered elements defining a substantially conical entrance portion of said assembly converging toward and leading to said exit portion, and means providing spaced cutting elements extending radially inward of said assembly adjacent the inner ends of said rollers.

4. In a roller assembly, a unitary race and a plurality of circularly caged rollers rotatably mounted therein, each comprising a cylindrical body portion having at its inner end an inwardly tapering element, the body portions of said rollers having bearing contact with the inner face of said race and defining a substantially cylindrical exit portion of said assembly and said tapered elements defining a substantially conical entrance portion of said assembly converging toward and leading to said exit portion, said assembly having outwardly opening radial slots in the zone of said tapered elements of said rollers, and means providing spaced cutting elements extending radially inward of said assembly adjacent the inner ends of said rollers.

WALTER A. CURTIS.

REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS Number Name Date 361,957 Mannesmann Apr. 26, 1887 411,060 Robertson Sept. 1'7. 1889 997,573 Michaud July 11, 1911 1,143,101 Brinkman June 15, 1915 1,312,936 Wilson Aug. 12, 1919 1,665,915 Ekman Dec. 21, 1925 1,993,427 Widuch Mar. 5, 1935 2,032,917 Cushwa Mar. 3, 1936 2,160,975 Matter et al June 6, 1939 2,198,540 Kooks et al. Apr. 23, 1940 

